Characterization of liquid-crystal displays for medical images Part 2

摘要

The paper presents methodologies for characterizing liquid crystal displays (LCDs) and the image quality of two new high-performance monochrome LCDs, a 2- and a 5-million-pixel display. The systems' image quality is described by on-axis characteristic curves, luminance range and contrast, luminance and contrast as a function of viewing angle, diffuse and specular reflection coefficients, color coordinates, luminance uniformity across the display screen, temporal response time and temporal modulation transfer function (MTF), spatial MTF, spatial noise power spectra and signal-to-noise ratios. The LCDs are equipped with an internal photosensor that maintains a desired maximum luminance and calibration to a given display function. The systems offer aperture and temporal modulation to place luminance levels with more than 12-bit precision on a desired display function and achieve very uniform contrast distribution over the luminance range. The LCDs have image quality that is superior in many respects to high-performance and high-resolution cathode-ray-tube (CRT) displays, except for the temporal MTF and the spatial noise. Spatial noise appears to be comparable to CRT display systems with P4 or P104 phosphor screens.